Personal cleansing compositions for removing dirt, oil, make-up, and like from skin are in wide use today and are marketed in a variety of forms such as creams, lotions, gels, bars, and astringents. Cold cream type cleansers are centuries old. Some of the earliest compositions were based on an animal fat or vegetable oil mixed with water and a fragrance. The fat or oil component of these early formulas was useful for removing oily debris from the skin, while the water component provided a lighter, smoother feel, and made the product easier to remove. These early compositions were unstable because the fat or oil component readily separated from the water component. These early compositions also had a short storage life because they would quickly become rancid. These early compositions were eventually improved by the addition of emulsifiers, stabilizers, antioxidants, and preservatives. Surfactants were also added to these compositions in an attempt to further improve their cleansing ability.
Cleansing compositions in the form of oil-in-water emulsions are preferred over water-in-oil emulsions because the former generally have a lighter, non-greasy, cleaner feel than the later. However, effective personal cleansing compositions are difficult to formulate as oil-in-water emulsions. An oil-in-water emulsion cleanser typically utilizes an emulsifier to keep the oil and water phases emulsified together for storage ability. This stability can actually hinder the cleansing ability of the emulsion if the oil phase is too tightly held and not released and available during the cleansing process. Furthermore, surfactants added to improve the cleansing ability of an emulsion cleanser can actually reduce cleansing ability, because the surfactant can also function as an emulsifier, thereby rendering both the surfactant and the oil phase less available for cleansing. One solution to this problem has been the development of nonemulsified two-phase cleansers. These cleansers are aesthetically unappealing, both visually and tactilely, and have the disadvantage of requiring vigorous agitation of the product prior to use.
U.S. Pat. No. 5,004,598, to Lochhead et al., issued Apr. 2, 1991, discloses mineral oil containing oil-in-water emulsions which also contain crosslinked long chain polymers, whereby the emulsion breaks upon contact with human skin. However, this document fails to teach the criticality of avoiding emulsifying surfactants, which can adversely affect the performance of a cleansing type emulsion. The compositions of the present invention comprise detersive, non-emulsifying surfactants having certain HLB requirements, as detailed below.
U.S. Pat. No. 5,011,681, to Ciotti et al, issued Apr. 30, 1991, discloses oil-in-water emulsions for removing make-up comprising a surfactant with an HLB greater than about 10, a polyalphaolefin, and a carboxylic acid copolymer containing C10-C30 substituents. However, the document does not teach that a cleansing emulsion is achievable without the polyalphaolefin. In fact, the cleansing emulsions of the present invention are achieved without relying on a polyalphaolefin and are required to be free from this component.
The compositions of the present invention utilize a carboxylic acid copolymer, as described herein, as an emulsifier. This emulsifier provides sufficient stability for storage of the product, and yet allows the product to de-emulsify or break on contact with the skin. Additionally, these compositions utilize a detersive, non-emulsifying surfactant for providing a boost in cleansing without interfering with the release of the oil phase during the cleansing process.
It is therefore an object of the present invention to provide compositions which are useful for personal cleansing.
It is another object of the present invention to provide oil-in-water emulsions which are stable and which also de-emulsify upon contact with the skin.
It is another object of the present invention to provide methods of personal cleansing.
These and other objects of this invention will become apparent in light of the following disclosure.